    <!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
        <script src="jquery.js"></script>
    </head>
    <body>
    <ul class="level-1">
        <li class="item-i">I</li>
        <li class="item-ii">II
            <ul class="level-2">
                <li class="item-a">A</li>
                <li class="item-b">B
                    <ul class="level-3">
                        <li class="item-1">1</li>
                        <li class="item-2">2</li>
                        <li class="item-3">3</li>
                    </ul>
                </li>
                <li class="item-c">C</li>
            </ul>
        </li>
        <li class="item-iii">III</li>
    </ul>
    <script>
        $('li.item-a').parents().css('background-color', 'red');
    </script>
    </body>
    </html>